Anthracene-based emitters for highly efficient deep blue organic light-emitting diodes with narrow emission spectrum

Abstract

Organic light-emitting diodes (OLEDs) are expected to support the future applications in flat-panel displays and solid-state lightings owing to their advantages of flexibility, light weight, high resolution, energy conservation, etc. Achieving efficient deep blue electroluminescence with excellent color purity (narrow emission) remains a big challenge for OLEDs. Herein, two anthracene derivatives, PIAnTPh and PyIAnTPh, with a hybridized local and charge transfer (HLCT) excited state are obtained by attaching the large periphery groups of phenanthroimidazole/pyrenoimidazole and terphenyl unit to the 9,10-positions of anthracene. The sterically asymmetric strategy can efficiently suppress the unfavorable intermolecular interactions and realize deep blue emission. The introduction of neutral terphenyl unit avoids the potential reduction of fluorescence quantum yield from strong charge transfer (CT) characteristics. More importantly, the relatively weak CT state and the rigid molecular structure can significantly reduce the vibrational motion to obtain relatively narrow emission spectra. The doped devices based on PIAnTPh and PyIAnTPh show strong deep blue electroluminescence with CIE coordinates of (0.15, 0.06) and (0.15, 0.07), high color purity, and narrow full width at half maxima (FWHM) of merely 50 and 52 nm, respectively, meeting well with the EBU standard. The EQEs are as high as 8.09% and 8.44% for PIAnTPh and PyIAnTPh, which are among the state-of-the-art deep blue OLEDs.